Mandelbulber 1.08. 2 color versions. Click the previews for 2560×1600 pixels.
So what’s that? A Mandelbulb?? Wikipedia explains it.
These two images were done with “Mandelbulber”, a nice piece of Open Source software. You can get it here. Another interesting link: Mandelbulb: The Unravelling of the Real 3D Mandelbrot Fractal.